Variable speed pulley



NOV- 1938- ij E. MCELROY ET AL 2,135,348

v VARIABLE SPEED PULLEY Filed Aug. s, 195e Patented Nov. 1, 1938 i l, y 2,135,348 Y UNITED `srlirlezs Pl-xTEN'rl OFFICE Isaac E. McElroy and Richard H. Shadrick,

Minneapolis, Minn., assignors to Minnesota Appliance Corporation,-,Minneapolis, Minn., a corporation of Minnesota i Application August 8, 1936, Serial N 94,956

,7 Claims. (Cl. 'i4-230.17)

This invention relates to variable speed power vcally through the pulley structure and showing transmission devices, and the primary object is the belt in operative position at a greatly reduced to provide an automatic diameter adjustable pulpulley diameter.

ley which is particularly an improvement over the Fig. 3 is a cross sectional elevation on the irregpulley construction disclosed and claimed in our ular line 3-3 in Fig. 1. 5 copending application Ser. No, 697,818, filed No- Fig. 4 is a side elevation similar to Fig. 1 but vember 13, 1933, for Variable speed pulley, which showing a belt in pulley constricting position and application matured into Patent No. 2,050,358 on with a portion of the pulley broken awayv to ex- August 1l, 1936. The present pulley operates on DOSe the inner COnstruCtiOn.

lo principles which are substantially similar to those Fig. 5 isI a sectional detail view on line 5-5 10 disclosed in the earlier application and for that in Fig 2, and

reason reference is made to the said Patent No. Fig. 6 iS a Secicnal detail View substantially 2,050,358 for a more complete explanation of the es 0n line 6-6 in Fig. 5. l construction, arrangement, and operation of Referring t0 the drawing more particularly and parts, which are essentially the same in both by reference charecteral designatesashaft upon 15 instances, which the pulley is mounted, and 8 designates While we have not departed from the fundethe belt by which power is to be transmitted to mental theories or construction evidenced by our a Seccrld 0r driven pulley. 0r, When SO desired the previous application, the practical and eommervariable or adjustable pulley may be the driven cial development and study which followed ompulley. In either event the effective belt groove '20 rearlier efforts haveresulted 1n changes and 1mdiameter of the variable pulleyis increased or provements which have greatly increased the emdecreased by respectively decreasins'or increasing ciency of the unit, while also adding to its life, the mean resistance or average tension between ruggedness, and smoothness of operation; These the tight and slack sides of the belt, and this can improvements include generally the following: be accomplished in Several ways, as pointed out in er,

Lengthening the effective bearing surfaces of thev 0111' Patent N0. 2,050,358. A

belt groove forming discs axially with respect to The pulley DrOPer includes a Central hub memthe supporting hub and without axially enlarging ber 9 Which iS axially reccSSed et One end t0 the pulley unit proper, to thereby reduce and receive the shaft 1, and the hub is non-rotatably eliminate all binding tendency or frictional re- Secured 0n the Shaft by Splinirlg 0r keying. eS 30 sistance in the mechanism while being adjusted indicated et i0 in Fiel 2- The hub 9 may be in response to variations in belt tension. The Secured against endWiSe displacement Orl the new pulley incorporates improved and novel Shaft by Set Screw il.

means for lubricating all moving parts, and this The end portion 0f hub 9, Opposite from shaft means includes a lubricant distribution method 'Lis provided with a conical chamber I 2, the 35 which is favorably responsive to the action of apex of which opens to the end of the hub for recentrlfugal force, particularly When the pulley is ceiving lubricating oil, and this it may be noted being operated at high speeds. The structure can be done even while the pulley is running; alSO contemplates the llSe 0f ccntaci driving The chamber I2 is separated from the shaft re- 40l blocks which are of sufficiently yieldable matecess by a tight tting plug I3 inserted from the 40 rial to produce a CuShiOhiIlg aciOrl, and thereby `larger or recess end of the hub, and the chameliminate chattering, vibration, jerking, etc., and ber |2 1S preferably lled with an absorbent y which blocks are also 0f absorben@ maternal packing material I(not shown) to retain the lu- Whereby they Wm retain a mbncant Q11 mld thus bricant or oil inserted through the axial end aplenminaife the otherwise frequent Occaslon for erture. The conical form of the chamber Wall ubrication of the contact surfaces. Still other Wm a th l b t t t th and more specic improvements and objects will c. use e u rcan. Commg m con ac. ere' be disclosed in the course of the following speci.- with to move or ow inwardly toward dlsgharge flcation, reference being had to the accompanyapertures l" under the amo? of @,entrlfugal ing drawing, wherein: force, while the absorbent packing will have a 50 Fig. 1 is a side elevation oi the'pulley as tendency t0 Prevent a i300 rapid discharge mounted on a motor or power shaft, but with through theapertures. In this manner the pulthe belt removed and the pulley discs in a position ley can quickly end easily be lubricated from forming a belt groove of maximum diameter', time to time, and while in operation if neces- Fig. 2 is a sectional elevation taken diametrisary, and the normal rotation will be effective to 55 movement occurs when the effective diameter of hold the entire pulley assemblytogether.

. important that the two shell members` be nonrotatably' secured with respect to each other i produce uniform feed of the lubricant to theV friction contact surfaces of the hub assembly..

'I'he shaft (1) end of the hub member 9 is provided with a flange I6 to which is rigidly secured by rivets I6 a plate I1 having an inwardly projecting peripheral ange I8, forming a generally cup shaped shell. A similarly formed but reversely faced shell I929 is secured by rivets 2I to a collar 22 that nts upon a reduced end of the hub 9 and is removably secured thereto by a nut 23 which also serves to releasably It is and to thatend we providean inner end of the collar member 22 with a pair of spaced lugs 24 for endwise engagement in notches 26 in the hub material (see Figs. 2,` 5, and 6).

A bearing sleeve 26 is' mounted on the hub member 9 and has freedom for limited oscillating and y'endwise movement thereon, such the pulley is changed and in order to reduce friction and insure proper automatic adjustment of the sleeve it must move freely on the hub.' For this reason the oil discharged through perforations I 4 `comes into direct contact with the in- The sleeve 26 supports the two groove forming pulley sections or discs 28 and 29, which sections are of the conical, telescopic type having interlaclng spokes 39. The section 29 is mounted on the right end of the sleeve 26, as shown in Fig. 2, and is rigidly secured thereto by any suitable means, in the present case it having a driving fit on the sleeve. Consequently the section 29 rotates with the sleeve 26 on the hub 8, and because of the long bearing surface for the sleeve there is no appreciable tendency of the section to bind or stick on the hub under the somewhat angular or oblique pressure resulting from the belt tension in the pulley groove.

\ The other pulley section, 28, is mounted for sliding movement on the sleeve 26, and in order that it may have as long an axial bearing sur-v face as possible, we provide it with a collared extension lI which slidablyvembraces the sleeve 26 and extends into a recess in the collar 22 as 'best shown in Figs; 2 and 6. As previously mentioned, the perforations 21 in the sleeve 26 permit a sumclent amount of oil to ow outwardly to provide proper lubricationA for the' when they are by any chance separated beyondl the position shown in Fig. 2, which sometimes occurs when the pulley groove is adjusted to its vvery smallest diameter. -A lsecond purpose of the key arrangement 33 is to insure the proper belt alignment and prevent any possibility'of the belt coming in contact with the flanges I8 or 20 when the pulley is adjusted to the large diameter condition, as shown in Fig. l.

Under such circumstances the key 32 moving to the' right with* section 26 projectsl beyond the right end of the sleeve 26, as shown in Fig. 2, to stop against ,the plate I1, and thereby prevent the longitudinal movement of the sections 28 and 29 beyond the' desired or normal position of rest, as might oc- 22. '-I'hese springs 36 and,38 do not in any way constitute driving or power transmission elements or connections as between-the hub 9 and 'the grooveforming discs 28 and 29. They do, however, 4have an important function in the normal operation of the pulley, and that is to establish the initial disc contact with the belt and to some extent assist in centering the discs in proper belt alignment as well as to eliminate noise and vibration. A further function-of the springs is to maintain belt contact in such a manner as to prevent the so-called surging action which sometimes develops in the powerline, and particularly when the driven shaft or element may l momentarily exceed the speed of the driving shaft or motor.

Driving connection from the hub 9 to the groove forming discs or members 28 and 29 is established through'a series of blocks 49 carried by the discs and arranged to contact with cam acting surfaces of strap members 4I rigidly secured to the inner surfaces of the plates I1 and I9. These members 4I are circular or ring shaped in plan (Fig. 3), but in side elevation or peripheral contour are reversely curved (Figs. 2 and 4), and in the present instance with three 4 serpentine undulations in each ring. The blocks 49 have freedom for limited oscillating movement between opposite cam surfaces and will contact withA such respective surfaces depending upon the direction of driving rotation. 'I'he position of the blocks with respect tothe highand low points of contact with the cams, or the spread between thel sections 28 and 29 forming the effective belt groove diameter, `is determined entirely by the belt tension. or rather by the mean tension between the tight and slack sides y of the belt, as explained more fully in our'Patent No. 2,050,358. In the prior case, however, the cam acting surfaces were metal to metal contact, and while operative did not prove enl tirely satisfactory when subjected to hard and long usage. 'It wasfound diiilcult to maintain the cam contacting surfaces lubricated as it was diillcult to apply the lubricant at sumciently frequent intervals, and centrifugal force tended to throw the lubricant away from the friction surfaces. Thls resulted in a certain amount of cutting, chattering, vibration, and noise. In the present instance, however, we have entirely elim' inated these objections and substantially improved the emciency andV smoothness of operation, by providing the wide contact surfaces 0f aisselle the rings Land by making theV blocks 40 of oil impregnated and slightly resilient material. vAs lthe undulated cam rings Il are only attached at peripherally spaced points they providea certain amount of resiliency against sharp contacts and shocks. Such actions, however, are primarily absorbed by the blocks 40 which are preferably o! wood or nbre, and being detachablecan be easily replaced if and when' necessary. Of greater significance, however, is the fact that the contact blocks are vformed of a material that is sumciently porous to receive and retain a lubricant fluid such as oil sothat the ring (4I-l engaging or contacting surface will at all times lbe 1,5 suiliciently lubricated to prevent destructive wear or objectionable noise. It will also of course be obvious. particularly when the blocks Ihave been impregnated under pressure, that the oil will be retained against the action of centrif- 20 ugalforce which is particularly noticeable at this distance from the axis o! rotation.

It is understood that suitablel modications may be made in the structure as disclosed, provided suchmodiilcations come within the spirit 25 and scope of the appended claims. Having nowV A therefore fully 'illustrated and describal our ,in-

vention, whatwe claim to be new and desire toprotect byLettersPatent is:

1. A variable .speed pulley comprising a hub $0 forming spindle, a sleeve slidably mounted on the spindle, a belt groove forming disc secured'rlgidly upon one end 'portion of the sleeve so as to be adjustable therewith, a second belt groove forming disc mounted upon the opposite endportion.

35 of the sleeve and slidable with respect thereto for adjustment relative the -ilrst mentioned disc to thereby permit 4adjustment of the effective diameter of the belt groove, and cam acting `means carried by opposite ends or the spindle o and for engagement with the respective discs to establish driving connections therewith.

2. A variable speedv pulley comprising a -hub forming spindle, a sleeve slidably mounted on the spindle, a belt groove forming disc secured rigidly.

45 upon one end portion ofthe sleeve so as to be adjustable therewith,` a second belt groove forml 3. A variable speed pulley comprising a hub lhaving a casing shell rigidly secured toone end,

a collar removably secured upon the other end of the hub and supporting a reversely faced com plemental casing shell, a sleeve slidably mounted on the hub, said collar having an annular groove adapted to receive one end of the sleeve, a pair,l

of belt groove forming conical discs mounted on thesleeve. and for axial adjustment to permit variance of the eiective belt groove diameter in response to changes in belt tension, and means establishing variable driving connections'between the discs and said casing shells.

4. A variable speed pulley vcomprising belt groove forming discs and means supporting the same for limited axial movement, side members supported adjacent the said discs and having cam acting surfaces adjacent to the said discs,`

and resilient, lubricant impregnated contact ele- --ments carried by the discs in contact with the said cam acting surfaces and eilective to permit limited oscillating movement of the discs.'

5. A variable speed pulley comprising a pair of belt groove forming discs, means vsupporting the discs for limited axial movement, a side member supported adjacent each disc and having cam acting surfaces turned toward the discs, and contact elements of resilient, lubricant impregnated lar strap member secured at circumferentially spaced points to each side member and having v intervening undulations 4extended toward the discs, and contact members of resilient, lubricant impregnated material rigidly secured to thediscs in sliding contact with the said strap members to thereby eil'ect limited oscillating -motion ofv the discs.

.7. A variable-.speed pulley comprising a pair y of belt groove forming discs, means axially supporting the discs for limited sliding motion toward and away from each other, side members supported adjacent the said discs, cam acting meanssupported by the side members adjacent the discs, and lubricant impregnated contact elements on the discs having slidable, contact with the cam acting means to thereby eilect limited axial and'osclllating movement of the discs. 

